In recent years, thermal transfer systems have been developed to obtain prints from pictures that have been generated from a camera or scanning device. According to one way of obtaining such prints, an electronic picture is first subjected to color separation by color filters. The respective color-separated images are then converted into electrical signals. These signals are then transmitted to a thermal printer. To obtain the print, a cyan, magenta or yellow dye-donor element is placed face-to-face with a dye receiver element. The two are then inserted between a thermal printing head and a platen roller. A line-type thermal printing head is used to apply heat from the back of the dye-donor sheet. The thermal printing head has many heating elements and is heated up sequentially in response to one of the cyan, magenta or yellow signals. The process is then repeated for the other colors. A color hard copy is thus obtained which corresponds to the original picture viewed on a screen.
Thermal dye receiver elements used in thermal dye transfer generally include a support (transparent or reflective) bearing on one side thereof a dye image-receiving layer, and optionally additional layers, such as a compliant or cushioning layer between the support and the dye receiving layer. The compliant layer provides insulation to keep heat generated by the thermal head at the surface of the print, and also provides close contact between the donor ribbon and receiving sheet which is essential for uniform print quality. Various approaches have been suggested for providing such a compliant layer. U.S. Pat. No. 5,244,861 (Campbell et al.) describes a composite film comprising a microvoided core layer and at least one substantially void-free thermoplastic skin layer. Such an approach adds an additional manufacturing step of laminating the composite film to the support, and film uniformity can be variable resulting in high waste factors. U.S. Pat. No. 6,372,689 (Kuga et al.) describes the use of a hollow particle layer between the support and dye receiving layer. Such hollow particles layers are frequently coated from aqueous solutions that necessitate a powerful drying stage in the manufacturing process and can reduce productivity. In addition, the hollow particles can result in increased surface roughness in the finished print that reduces surface gloss. It would be advantageous to provide a compliant layer that enables a high gloss print to be obtained. It would also be advantageous if the technology used to provide such a compliant layer also enables a matte-like print to be obtained if a low gloss finish is desired. It would be further advantageous if this low gloss finish can further be enhanced by the incorporation of additives like matte beads in an aqueous subbing layer.
Known polymer composite laminates used on the faceside (imaging side) of dye-thermal receiver elements have a top skin layer of polypropylene (PP) onto which can be extruded a dye receiver layer (DRL), or an image receiving layer, containing a polyester/polycarbonate blend.
Copending and commonly assigned U.S. Ser. Nos. 12/490,464 and 12/490,464 (both filed Jun. 24, 2009 by Dontula et al.) describe imaging elements having multiple extruded layers included extruded compliant and antistatic subbing layers. Two or more of such layers can be co-extruded if desired along with optional extruded skin layers.
In addition, copending and commonly assigned U.S. Ser. No. 11/681,802 (filed Mar. 5, 2007 by Majumdar and Dontula) describes image recording elements comprising a support having thereon an aqueous subbing layer and an extruded dye receiving layer.
U.S. Pat. No. 4,775,657 (Harrison et al.) describes the use of organic solvent-coated overcoats in thermal dye transfer elements, which overcoats containing polycondensation polymers having a glass transition temperature that is at least 40° C. less than the Tg of the organic solvent-coated dye image receiving layer. This difference in Tg tends to cause sticking of the element during thermal dye transfer. In addition, because of the high Tg of the dye image receiving layer polycarbonate, these elements tend to exhibit dye instability and unwanted dye migration
While aqueous antistatic layers have been inserted between extruded compliant layers and extruded image receiving layers, there is a desire to avoid such layers if possible. In addition, there is a desired to use less expensive and easily applied (extruded) image receiving layers that are simple in construction and yet can be readily used for thermal printing without jamming in printers.